The overarching goal of this Senior Scientist Award (K05) application is to provide the candidate with a period of stable funding in which to conduct full-time programmatic research on the developmental patterning of familial transmission of biobehavioral factors that contribute to the transgenerational manifestations of conduct deviation and substance use disorders (SUD). The emerging discipline of developmental psychopathology attempts to elucidate the etiology, course, and sequelae of conditions such as SUD, Conduct Disorder (CD), and Antisocial Personality Disorder (ASPD) through the integration of knowledge from multiple disciplines such as psychology, psychiatry, genetics, epidemiology and neuroscience within a developmental orientation. Basic researchers and theorists have posited that critical developmental periods exist when particular familial or unique environmental factors are most influential in determining an adverse psychopathological phenotype. Limited research has been conducted on the presence and timing of critical developmental periods in the etiology of CD, ASPD and SUD, yet such information is vital to the efficacious timing and nature of targeted drug abuse prevention interventions. The proposed program of investigation aims to undertake systematic prospective research into the nature and predictors of transmissible and non-transmissible developmental risk for conduct deviancy, substance use and SUDs beginning in the prepubertal period and continuing across the transition from childhood to adolescence and young adulthood. The research will also examine sex heterogeneity of transmissible influences. The existence of sex heterogeneity is plausible since differential transmission effects have been described between same- sex-parent to child transmission for externalizing behaviors. The results have important implications for drug abuse prevention.